The present invention relates to telescoping platform assemblies configured to support a movable platform, and particularly to modular telescoping platform assemblies comprising two or more telescoping slide assembly modules attached to each other. More particularly, the present invention relates to modular telescoping platform assemblies having automatic extension and retraction capability to multiply the effective reach of a driving mechanism.
Telescoping slide assemblies generally comprise two or more interconnected slide members that are free to travel in a back and forth motion relative to each other. Typical uses for such slide assemblies include support for file drawers and equipment racks for inward and outward movement of the drawer or rack relative to a frame. Some slide assemblies incorporate pulley and cable systems to promote synchronized extension of the telescoping slide assemblies. See, for example, U.S. Pat. No. 3,687,505 to Fall et al.
Typically, the slide assemblies are manually operated. However, in those situations where heavy equipment is to be extended or retracted, a powered driver would be necessary. Mechanical or hydraulic powered operation may be difficult, however, since the powered driver may be required to extend substantially the same length as the telescoping assembly itself. In mobile vehicles or other applications having limited space, insufficient room is available to accommodate lengthy powered drivers.
According to the present invention, a telescoping platform assembly comprises a plurality of slide members including interconnected first, second, third, fourth, and fifth slide members. It further includes means for extending the slide members so that movement of the second slide member over a predetermined distance relative to the first slide member results in movement of the fifth slide member over four times the predetermined distance relative to the first slide member to extend the telescoping platform from a home position to a fully extended position. The telescoping platform assembly further comprises means for retracting the slide members so that movement of the second slide member over a predetermined distance relative to the first slide member results in movement of the fifth slide member over four times the predetermined distance relative to the first slide member to retract the telescoping platform from an extended position to a fully retracted position.
One application for long-reaching telescoping platform assembly in accordance with the present invention is a situation in which it is necessary to move a piece of equipment a fairly long distance on an extension mechanism using a hydraulic cylinder and the available space is so small that only a hydraulic cylinder or other driver having a short stroke can be used. For example, a machine that weighs 1000 pounds has to be supported in a storage position and occasionally moved from its storage position across an aisle in order to engage a second machine. Later, it will be necessary to retract the extension mechanism and the heavy machine to its storage position to clear the aisle. The extension mechanism is space-limited to a maximum of 40 inches when retracted, but must extend a total of 80 inches for the machine to be moved across the aisle to perform its function. A telescoping platform assembly in accordance with the present invention is able to convert each unit of distance moved by the driver into two, four, or greater number of units of rail extension and represents an improvement over conventional telescoping platform assemblies. Such a telescoping platform assembly, would allow the use of a 20 inch driver yet be operable to extend the heavy machine a distance of 80 inches. A 20 inch driver falls well within the space limitations and yet still allows the machine to perform its function.
In preferred embodiments, the means for extending includes a first extension pulley fixed to the second slide member and a first cable attached to the first slide member and the third member and passing over the first pulley. It also includes a second extension pulley which is attached to the third slide member and a second extension cable which is attached to the second slide member and the fourth slide member and passing over the second extension pulley. The means for extending further includes a third extension pulley fixed to the fourth slide member and a third extension cable attached to the third slide member and fifth slide member and passing over the third extension pulley. These pulleys and cables cooperate to extend the effective reach of the telescoping platform assembly without increasing the length of the stroke of the driver used to extend the platform.
The means for retracting the slide members includes a first retraction pulley attached to the second slide member and a first retraction cable fixed to the first slide member and the third slide member and passing over the first retraction pulley. It further includes a second retraction pulley and a second retraction cable which is fixed to the second slide member and the fourth slide member and passes over the second retraction pulley. The means for retracting further includes a third retraction pulley fixed to the fourth slide member and a third retraction cable fixed to the third slide member and the fifth slide member and passing over the third retraction pulley. These retraction pulleys and cables cooperate with the above-noted extension pulleys and cables to make it possible for the same short stroke driver to retract the telescoping platform assembly simply by reversing the driver.
A telescoping platform assembly in accordance with the present invention is capable of multiplying or extending the reach of a driving mechanism. The telescoping platform assembly can thereby extend a platform supporting a heavy machine from a home position to a fully extended position that is far beyond the longest reach available to the driving mechanism. Advantageously, short stroke driving mechanisms can be used to extend telescoping slide assemblies relatively long-distances. This is particularly useful, in applications where a telescoping slide assembly must be capable of having a long reach and space restrictions will only permit use of a short stroke driving mechanism.
Furthermore, the means for retracting the slide members in accordance with the present invention allows a driving mechanism to fully retract the telescoping platform assembly from an extended position which would otherwise be beyond the reach of the driving mechanism to a fully retracted, or home position. By allowing extension of the platform assembly out to four, six, eight, or more times the extension of the driving mechanism, the present invention provides a greater effective reach given the small input and a substantial improvement over conventional extension devices.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.